Let's talk about Reliability. Why should we trust relative humidity?
Well, as seen on this next schematic drawing, the Finish Floor System actually "sees" relative humidity. When you looked at a floor system, think about this, a concrete has been sitting there for some time, it may have been drying out, there's some amount of moisture in the slab and coming out. And as soon as the floor slab is covered, there's no longer any emission.
By definition, you've capped the surface and now the moisture within the slab is going to even itself out.
This schematic drawing shows two different floor slabs. The one on the left-hand side has a lower moisture condition, while the right-hand side has a higher moisture condition. Because their floor covering is in place, you cannot measure moisture emission. But, there are two moisture conditions; the right-hand system had actually failed because the moisture level is very high. You can go a head and drill a hole and put a probe into the floor with the floor covering in place and see the true moisture picture in the concrete underneath the floor covering.
And if you're investigating a floor covering failure, that's the way to get the true moisture picture after the floor covering or coating has put in placed. But, there is no emission by the time that the floor covering is actually in place on the floor.